<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    .box {
      width: 200px;
      height: 200px;
      background-color: rgb(187, 150, 156);
    }
  </style>
</head>
<body>
  <div id="app">
    <div class="box" :style="{ width:'400px' , height:'400px', backgroundColor:'green'}"></div>
  </div>
  <script src="../js/vue.js"></script>
  <script>
    const app = new Vue({
      el: '#app',
      data: {

      }
    })
  </script>
</body>
</html>